The present invention relates to aircraft of the type having a cabin defined within a wing of the aircraft. More particularly, the invention relates to an aft egress device providing access to the cabin of such an aircraft and to an aircraft having such an aft egress device.
The economics of commercial air transport for passengers and/or cargo in many cases favor larger-capacity aircraft. Accordingly, aircraft designs are being contemplated which would enable capacity to be increased substantially above the largest aircraft that are currently available. Among the aircraft configurations being studied are aircraft having the passenger cabin and/or cargo compartments within the wing rather than (or in addition to) within the fuselage. Such aircraft are referred to herein as xe2x80x9cblended wing-bodyxe2x80x9d aircraft, but it will be understood that the invention is not limited to any particular aircraft configuration and applies to any aircraft having a cabin or compartment within a wing.
Conventional aircraft having the cabin in the fuselage typically have lateral doors for entering and exiting the cabin through the sides of the fuselage. In blended wing-body aircraft, however, it is not practical to employ lateral doors, because in many of these aircraft the inboard portions of the wing are used for passenger cabins while the outboard portions of the wing are devoted to fuel storage and/or cargo holds which prevent lateral access to the cabins. Accordingly, the primary access doors to the cabins in many blended wing-body aircraft currently being considered are in the leading edge of the wing. This area is removed from most of the major systems (engines, controls, hydraulic systems, etc.) of the aircraft so that access doors do not conflict with such systems. However, in order to meet regulations requiring complete evacuation of the aircraft within a given time period, it is necessary in some cases to have additional exits beyond those in the leading edge area of the aircraft wing.
Emergency evacuation requirements impose additional constraints on the design of all aircraft including blended wing-body type aircraft. The exit paths must not be too steep either ascending or descending. For the consideration of a water landing, the exits should be above the water line. The exit opening should have sufficient cross section to accommodate the required flow rate of passengers. The exits also should function when the aircraft is on any combination of gear struts when one or more of the struts fail or fail to extend. Such requirements in some cases may rule out some locations which might be considered candidates for additional exits from the cabin of a blended wing-body aircraft. For instance, the requirement that the egress still function in a water landing and when the aircraft is on its belly (i.e., all landing gear up) may rule out locating the egress in the wing lower surface.
Additionally, in the case of commercial passenger aircraft, it is desirable to be able to service the aircraft (e.g., clean the cabin, remove used food carts and replace with new ones, etc.) as quickly as possible in order to keep ground time to a minimum. Since primary access to the cabins for the passengers is through the wing leading edge, the forward areas of the cabins can become congested during deplaning and boarding, so that cabin servicing may need to be completed before passenger loading can begin. This can cause a significant delay. Thus, it would be desirable to provide additional access openings to the cabin area enabling service crews to service the cabin simultaneous with passenger boarding. However, the possible locations of such access openings are limited by the aforementioned considerations.
The above needs are met and other objects and advantages are achieved by the present invention, which provides an aircraft having an aft egress device which provides access to the cabin through a trailing edge portion of the wing. Although the trailing edge of the wing is usually devoted to variable control surfaces such as pitch controllers, and may also accommodate engines, hydraulic systems, and other systems, the invention nevertheless enables an aft egress to be located in the trailing edge of the wing. To this end, in preferred embodiments of the invention, the aft egress device performs dual functions of providing access to the cabin and serving as a variable control surface for the aircraft.
In one preferred embodiment of the invention, the aircraft comprises a wing having upper and lower aerodynamic surfaces extending between a leading edge and a trailing edge of the wing, and a cabin defined in an interior of the wing and having an aft end extending proximate the trailing edge of the wing. The cabin has an opening in the aft end thereof for entry to and exit from the cabin. The aircraft further includes a wedge-shaped trailing edge portion of the wing which is juxtaposed with the opening in the cabin, the trailing edge portion having an open interior and including a panel which is pivotable into an open position so as to define a door or passage in the trailing edge portion through which the opening in the cabin is accessible. The trailing edge portion of the wing thus serves as an aft egress device for access to and egress from the cabin.
Preferably, the trailing edge portion of the wing is formed by upper and lower panels which converge toward their aft edges. In one embodiment, the upper panel which forms an upper surface of the trailing edge portion is pivotable about a forward end thereof so as to perform dual functions of acting as a door which is opened to provide access to the cabin and serving as a control surface for the aircraft when suitably controlled by an actuator. Instead of or in addition to the pivotable upper panel, the lower panel which forms a lower surface of the trailing edge portion may be pivotable about a forward end of the lower panel so as to extend down from the wing. The lower panel may thus serve as an aerodynamic control surface and/or as an emergency slide for evacuation of the cabin. In some preferred embodiments, the upper and lower panels are pivotable in unison so that the entire trailing edge portion of the wing forms a variable control surface. Additionally, in other preferred embodiments the upper and lower panels may be independently actuated during flight. For example, the panels may split apart for reasons such as aerodynamic braking on a landing roll.
The lower panel preferably is pivotable into a generally horizontal position so as to serve as a ramp for loading and unloading passengers, crew members, and/or cargo into and out of the cabin.
In another preferred embodiment of the invention, the wedge-shaped trailing edge portion is formed by an upper panel and a lower panel each having a forward end and an aft end, one of the upper and lower panels being pivotally connected at the forward end thereof to the wing and the other panel being pivotally connected at the forward end thereof to the one panel. The aft egress device further comprises a latch which releasably secures the upper panel to the lower panel such that pivotal movement of one panel causes the other panel to pivot in unison therewith. An actuator engages the one panel and operates to pivot the one panel, whereby the trailing edge portion of the wing is pivotable. The aft egress device advantageously includes a spring which biases the upper and lower panels pivotally away from each other such that upon release of the latch the panels are pivotally moved apart so that at least one of the panels assumes an open position creating the passage for entry and exit through the access opening between the panels.
It will thus be appreciated that the invention meets the aforementioned needs by providing an aircraft having one or more aft egress devices which can serve as additional exits for emergency evacuation of the aircraft, and can also serve as access passages for service crews to service the aircraft from the rear, thus allowing passengers to board the aircraft through forward doors while service crew members simultaneously service the aircraft. At the same time, where the aft egress device also serves as a variable control surface, the invention enables aft access passages to be provided without conflicting with the requirement of providing control surfaces for the aircraft.